Rheostat.



PATENTBD MAR. 22, 1904.

'A. G. EASTWOOD RHEOSTAT.

APPLIOATION FILED DBO. 21, 1903.

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PATENTED MAR. 22, 1904. VA. 0. EASTWOOD.

RHEOSTAT. APPLICATION FILED 11mm, 1903.

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No. 755,468.' PATENTED MAR. 22, 1904.

- A. c. EASTWOOD.

RHEOSTAT.

APPLIOATION FILED DEG. 21, 1903.

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PATENT OEEICE.

ARTHUR O. EASTWOOD, CLEVELAND, OHIO.

RHEOSTAT.

SPECIFICATION forming part of Letters Patent No. 755,468, dated March22, 1904.

Application filed December 21, 1903. Serial No. 186,141. (No model.)

To all whmn it may concern:

Be it known that I, ARTHUR O. EASTWOOD, a citizen of the United States,residing in Cleveland, Ohio, have invented certain Improvements inRheostats, of which the following is a specification.

My invention relates to certain improvements in that class of apparatusespecially designed for the absorption and dissipation of electricalenergy, and has for its object the production of a rheostat composed ofa number of sections so arranged that all wiring connectionsbetween themand the corresponding contacts on the controller shall be eliminated. Itis further desired that the rheostat shall be of a simple and durableconstruction and shall consist of a relatively small number of parts ofsuch a nature that they can be manufactured and assembled with aminimum,

of labor and expense. These objects I attain as hereinafter set forth,reference being had to the accompanying drawings, in which Figure 1 is aplan view of one ofthe sections forming part of my improved rheostat.Fig. 2 is an end elevation of the rheostat-section shown in Fig. 1. Fig.3 is a sectional elevation on the line 3 3, Fig. 1. Fig. 4 is a sideelevation of my improved rheostat with its parts in their assembledpositions. Fig. 5 is a side elevation of a portion of my improvedrheostat. Fig. 6 is a sectional plan view on the line 6 6, Fig. 4. Fig.7is a diagrammatic view showing the electrical connections of therheostat. Fig. 8 is a plan view of a special form of section for myimproved rheostat, and Fig. 9 is an end elevation of the section shownin Fig. 8.

In the above drawings, A is a flat plate or grid of metal having at eachend projecting portions provided with bosses a, in which are formedholes for the reception of vertical bars at. These bars are suitablyfitted into the frame B of the rheostat, which preferably is of thegeneral construction shown in Fig. 4.

Extending in the plane of the plate A and held thereto by thescrews a isa spring contact-finger a which carries at its end a contact-button oand is in electrical connection with the body of said-plate. A screw apasses through the spring-finger a and bears against the end of theplate A, being provided with a jam-nut, as shown, whereby it may be keptfrom turning after having been adjusted in said finger.

Upon the body or main portion of the plate A is placed a covering ofmica 6, preferably shellacked in place, and upon this is cemented a thinlayer of asbestos paper Z2 asolution of silicate of soda beingpreferably employed as a cement. Over this body of insulating materialis wound a suitable resistance material, (indicated at 12 this being inthe form of a coil of wire which at one end is electrically connected tothe metallic body of the plate A by means of a screw 1) and at the otherend is passed through openings in an insulating-washer 5 held in thebody of the supporting-grid, so as to be firmly retained in positionwhile being free for connection to an adjoining section.

In assembling the various sections they are placed. one above the other,as shown in Figs. 4: and 5, with insulating-washers 0 between theadjacent bosses a, and the free end of the resistance-wire of each gridis clamped under the screw 6 of each resistance-section next adjacent toit, it being noted that said sections are for this purpose alternatelyplaced end for end'upon the supporting-rods a.

Carried upon a vertical shaft adjacent to the vertical column ofresistance-sections is a metallic cylinder D, having riveted orotherwise suitably attached to its outside surface a series of contactsd, so placed as to successively engage with the spring contact-fingers awhen the cylinder D is turned by means of its handle d. If desired, thesaid cylinder may be made of cast-iron and the contact-buttons of brass,these latter being provided with an asbestos washer d held between theirhead portions and the body of the cylinder, so as to prevent thepossible formation of an are between the contact-finger and saidcylinder.

The relative arrangement of electrical connections is preferably thatshown in Fig. 7 in which the contacted are placed upon the surface ofthe cylinder in a spiral line, so as to successively come in engagementwith the spring contact-fingers a whoseends lie in a straight line andwhich are connected to the various resistance-sections. In the presentinstance only the alternate resistance-sections are provided withcontact-lingers, although it will be understood that any desired numberof resistance-sections may be made to serve as a unit in the rheostatconsidered as a whole.

One of the contacts d on the cylinder D is in the form of a portion of aring and is placed in the present case so as to be opposite thelowermost contact-finger, which is in direct connection with one of thecurrent-mains E and E.

As long as the controller-cylinder D is in operation the lowermostcontact-finger is in engagement with the long contact-plate (Z and withthe connections shown in Fig. '7 all of the resistance comprised by thefive re sistance units is in series with the two currentmains E and E,while when the cylinder D is turned sufliciently far to bring the twolowermost contact-fingers a in engagement with the contact (Z andlowermost of the small brass contacts (Z, respectively, it will be seenthat the lowermost section of resistance a is short-circuited. Sincesaid contact (Z and the contact-ring (Z are provided with alow-resistance connection through the body of the metallic cylinder D,as the said cylinder is still farther rotated on its axis the varioussections of resistance '1", r 1", and 1- are successively cut out, untilfinally the current from the main E enters the highest of thecontactbuttons (Z and passing through the metallic body of the cylinderD finally flows out through the contact-plate (Z and the lowermost ofthe spring-fingers (0 It will be noted in Fig. 4: thatIhave shown aspring contact-finger mounted on every second grid, so that two units ofresistance form a section. It is evident, however, that by mounting asimilar set of fingers on the op: posite ends of the grids and providingthe necessary contacts one section may be cut out at a time.

When it is desired to employ my improved rheostat in connection withapparatus requiring heavy currents, I employ resistance-sections of theconstruction shown in Figs. Sand 9, in which the body of the grid A ismade to serve as the resistance material. In practice this form of gridis usually of cast-iron and constructed with any number of slotsextending into its body from its edges, so that it forms a relativelylong and continuous conductor. As in the case of the supportinggrid A,it has bosses at, of which there are in the present instance two on oneside and one on the other for the reception of the bars a belonging tothe supporting-framework of the rheostat. Similarly, the contact-fingera is in direct electrical connection with the body of the grid, therethus being, as in the other form of my invention, no connections orsecondary contacts between the spring-finger and the resistancematerial.

In the structure shown in Figs. 8 and 9 one of the bosses at has acontact-finger connected to it, while a second boss serves for theattachment of a metallic piece a, through which current flows to one ofthe resistance-sections next adjoining.

I claim as my invention 1. A resistance-section consisting of a metallicsupporting-body, a resistance material wound thereon, and electricallyconnected to said body, with a piece for making electrical contact alsoconnected to said body, substantially as described.

2. A resistance-section consisting of a metallic plate, a covering ofinsulating material therefor, resistance material wound on said plateand electrically connected thereto, and a contact also connected to theplate, substantially as described.

3. A rheostat consisting of sections of re sistance each including ametallic body having a winding in electrical contact therewith, meansfor connecting together the windings of the several sections, contactscarried by the metallic bodies of the sections and a movable elementalso having contacts placed to coact with the contacts on said sections,substantially as described.

4. In a rheostat, the combination of a series of metallic plates,windings on the plates in electrical connection therewith, metalliclingers in electrical connection with the plates and a movable elementplaced to engage said fingers. substantially as described.

5. In a rheostat, the combination of a series of supporting-grids eachhaving a Winding of resistance material, contact-fingers carried bycertain of the grids and in electrical contact with the windingsthereon, with an element carrying contacts for engagement with thefingers, substantially as described.

6. In a rheostat the combination of a wind ing of resistance material, aseries of contactfingers connected thereto at intervals, with a metalliccylinder having a series of contact plates projecting from and inelectrical connection with it, substantially as described.

7. The combination of a body ofresistance material havingcontact-fingers connected to it at intervals, a metallic cylinder havingcontact-pieces in electrical contact with it, said contact-pieces beingprovided with washers of insulating material between them and saidcylinder, substantially as described.

8. The combination in a rheostat of a frame, a standard thereon, aseries of metallic plates having portions in engagement with saidstandard, windings of resistance material upon the plates,contact-fingers in electrical connection with certain of the plates andwith the windings thereon, with an element carrying contacts forengagement with said lingers, substantially as described.

9. A resistance-section consisting of a plate of metal, a winding ofresistance material thereon connected at one end to said plate, and

a finger also in electrical connection with the plate and having meanswhereby it may be adjusted, substantially as described.

10. A section of a rheostat consisting of a metallic plate, a winding ofresistance material thereon, means for holding said plate in position ona frame, a finger projecting from said plate in the plane thereof, saidfinger being in electrical connection with the winding on the plate,substantially as described.

11. The combination in a rheostat of a supporting ,frame, a series ofplates thereon, windings of resistance material on the plates and inelectrical connection therewith, with means for connecting together thewindings of adjacent plates and means for insulating said plates fromeach other, substantially as described.

12. The combination in a rheostat of a series of plates having means forretaining them in position and contact-fingers projecting from them, aresistance'material wound on said plates and connected to said fingers,with a rotatable cylinder having its axis parallel to the axis of theseries of plates and contact-plates on said cylinder for engagement withsaid fingers, substantially as described.

13. A resistance -section consisting of a metallic grid, with acontactfinger mechanically attached to and in electrical contact withsaid grid, substantially as described. 14:. A rheostat consisting ofaseries of grids formed of electrically conducting material,

means for electrically connecting said grids together, contact-fingersconnected directly to the grids and contacts for coacting with saidfingers, substantially as described.

15. A resistance-section including a metallic plate anda contact-piecein mechanical and electrical connection therewith, said piece beingconstructed to slidingly engage another contact or contacts,substantially as described.

16. A resistance-section including a metallic plate and a contact-fingermechanically and electrically connected therewith, substantially asdescribed.

17. In an electric controller, the combination of a series ofcontact-fingers with a metallic cylinder having contacts thereon andwashers of insulating material between said contacts and the surface ofthe cylinder, substantially as described.

18. A resistance-section including ametallic plate and a contact-fingermechanically and electrically connected therewith, with means foradjusting the position of said finger relatively to a surface engagedthereby, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

ARTHUR c. EASTWOOD.

Witnesses:

C. W. CoMs'rocK, HOWARD O. Town.

